One of the largest studies of its kind shows that stenting and surgery to reduce narrowing of the carotid artery and restore normal blood flow are equally effective at lowering the long-term risk of stroke.
The latest results of the randomized stroke prevention trial CREST (Carotid Revascularization Endarterectomy versus Stenting Trial) are published in the New England Journal of Medicine and were recently presented at the American Heart Association’s International Stroke Conference in Los Angeles, CA.
There are around 800,000 strokes a year in the US, and 5-10% of them are caused by narrowing of the carotid artery.
Each person has two carotid arteries – they run up each side of the neck and carry oxygen-rich blood to the head, brain and face. However, a condition called atherosclerosis can cause plaque to build up on the inside of the artery wall, which leads to narrowing and hardening of the blood vessel (stenosis).
As the plaque – consisting of fats, calcium and cellular debris – builds up, it reduces blood flow and also introduces the risk of clotting, which can result in a stroke, where a part of the brain loses its blood supply.
There are currently two procedures to correct this – surgery and stenting. The surgical procedure – called carotid endarterectomy – involves making incisions to remove the narrowed segment of artery, while stenting involves inserting a catheter to place a small tube called a stent in the narrowed artery to widen it and keep it open.
For the trial – led by the Mayo Clinic in Florida – investigators followed over 2,500 patients with narrowed carotid arteries of an average age of 69 for up to 10 years. They were randomly assigned to receive stenting or endarterectomy at 117 centers in the US and Canada.
The results showed that the risk of stroke following either procedure was about 7%.
Principal investigator Thomas G. Brott, a professor of neurosciences at Mayo, says:
“This very low rate shows these two procedures are safe and are also very durable in preventing stroke.”
Because seniors with carotid artery narrowing are living longer, he notes, “the durability of stenting and surgery will be reassuring to the patients and their families.”
The study also looked for signs of re-narrowing of the carotid artery following either of the two procedures and found this also was low for both of them – about 1% per year.
Both procedures were equally effective regardless of age, gender and whether patients had previously suffered a stroke or not, say the researchers.
In 2010, early results of CREST found stenting and surgery to be equally safe, with fewer strokes among those who had surgery and fewer heart attacks among those who received stents.
These latest results complete a story, and the results are very encouraging, says Prof. Brott, who sums up the findings:
“We have two safe procedures. We know now that they are very effective in the long run. Now the patient and the physician have the option to select surgery or stenting, based on that individual patient’s medical condition and preferences.”
However, despite these promising trial results, the question of how best to manage stroke risk – especially in asymptomatic patients is not yet resolved. Asymptomatic patients are patients who have carotid artery narrowing but have not yet suffered symptoms, such as a non-disabling stroke or transient ischemic attack.
This is the purpose of CREST-2, a trial that compares stenting and surgery to medical management. It was launched in December 2014 and will run until the end of 2022.
In an accompanying editorial where they discuss the latest CREST findings and those of another trial called ACT I – the findings of which are also published in the same journal issue – Dr. David Spence, of the Western University in Ontario, Canada, and Dr. A. Ross Naylor, of Leicester Royal Infirmary in the UK, warn of the dangers of interpreting the trial results uncritically.
They express a number of concerns – especially with regard to asymptomatic patients – about the transition from the well-controlled conditions of the trial situation to clinical practice. They commend both trials for using credentialing for ensuring that only the best practitioners carried out the procedures.
But they are not so sure the low rates of death and stroke seen in the trials will translate to the clinic, especially if “guidelines are changed to further liberalize indications for stenting, especially in asymptomatic patients.”
They draw attention to the situation in the US, where “more than 90% of carotid-artery interventions are performed in asymptomatic patients, even though evidence suggests that up to 90% of them will undergo an ultimately unnecessary and potentially harmful procedure.”
They contrast this to rates in other countries. For example, “60% in Germany and Italy, 15% in Canada and Australia, and 0% in Denmark,” and note:
“Such discrepancies call into question the appropriateness of advocating routine interventions for asymptomatic carotid-artery stenosis.”
“Pending the completion of CREST-2, we think that it would be desirable for interventionists and surgeons to forgo stenting and endarterectomy in low-risk asymptomatic patients outside that trial,” they suggest.
In August 2015, Medical News Today reported how researchers developed and tested a new type of artificial blood vessel coating that shows promise in helping to prevent blood clots.